However, the energy provider expects a number of challenges in 2019, with cash flow to be affected by the rise in energy price caps by regulator Ofgem. It expects a one-off £70 million hit in the first period of the cap.

ITV News Consumer Editor Chris Choi says 11,000,000 energy customers across the country have now had price rises confirmed 1 April 2019.

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Last July, the Government passed a Bill which called on Ofgem to impose a cap on all default energy tariffs, including the standard variable tariff, which came into effect at the start of the year.

Centrica is aiming for operating cash flow to be between £1.8 billion to £2 billion in 2019, which is below the targeted range of £2.1 billion to £2.3 billion on average over 2018-2020.

Group chief executive Iain Conn said: “Centrica’s financial performance in 2018 was mixed against a challenging external backdrop. At the headline level, adjusted operating profit was up 12% and adjusted operating cash flow and net debt were within our target ranges.

“However, volumes in Spirit Energy and nuclear were disappointing and recovery in North America business was slower than expected.

Centrica chief executive Iain Conn Credit: Dominic Lipinski/PA

“Our 2019 financial performance will be impacted by the UK default tariff cap and continuing lower volumes in E&P (exploration and production) and nuclear, meaning our 2018-20 target range for average adjusted operating cash flow is under some pressure.”

He added: “We are taking actions to strengthen the company in 2019 and improve underlying performance in 2020, including driving cost efficiency hard and delivering further divestments, and as a result net debt levels remain underpinned.”

Centrica expects to make £250 million of savings in 2019 and is targeting an additional £500 million of savings beyond this year.